First Experimental Demonstration of Robust HZO/β-Ga₂O₃ Ferroelectric Field-Effect Transistors as Synaptic Devices for Artificial Intelligence Applications in a High-Temperature Environment

Abstract

We have experimentally demonstrated robust beta-gallium oxide ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) ferroelectric (FE) field-effect transistors (FeFETs) on a sapphire substrate operated up to 400 °C. Atomic layer deposited (ALD) Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> [hafnium zirconium oxide (HZO)] is used as the FE dielectric. The HZO/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> FeFETs are studied for their synaptic behavior applications at elevated temperatures. The devices show distinguishable polarization switching operation with the output conductance quasi-linearly controlled by the number of input pulses on the FE gate. In a simulation, on-chip learning accuracy reaches 94% at elevated temperatures using the Modified National Institute of Standards and Technology (MNIST) data set with a simple two-layer multilayer perceptron (MLP) network. These ultra wide bandgap semiconductor devices have the potential to fill the need for harsh environment neuromorphic applications.